1. Field of the Invention
This invention relates to a wiper apparatus with wiper blades used for wiping raindrops and extraneous matters away from windshield and the like of, for example, a motor vehicle, and more particularly to a wiper controller which is possible to actuate a plurality of wiper blades synchronously by a plurality of wiper motors and possible to set a plurality of wiping operations at the time of an intermittent operation of the wiper blade.
2. Description of the Prior Art
Heretofore, there has been used a wiper apparatus shown in FIG. 5, for example.
A wiper apparatus 100 shown in the FIG. 5 comprises wiper motors 101 and 102 of which motor shafts 101a and 102a is connected through linkages 54 and 55 with wiper blades 52 and 53 to wipe window glasses 50 and 51 respectively; a controller 103 composed of relays RL20 and RL21, transistors Tr20, Tr21 and Tr22, capacitors C20 and C21, and diodes D20, D21, D22 and D23; and a wiper switch 104. And the wiper motors 101 and 102 are provided with autostop switches 105 and 106 linked with the motor shafts 101a and 102a, respectively, and movable contacts 105a and 106a of the autostop switches 105 and 106 are so structured as to come in contact with normal-closed fixed contacts 105b and 106b grounded when the wiper blades 52 and 53 are located in stop positions (lower turning positions) D and E on the window glasses 50 and 51, and so structured as to come contact with normal-opened fixed contacts 105c and 106c connected to a power source 200 through an ignition switch 201 when the wiper blades 52 and 53 are located out of the stop positions D and E.
By switching on the ignition switch 201, H-level potential is applied to the bases of the transistors Tr20 and Tr21. And by changing the wiper switch 104 into a INT position (intermittent mode), a terminal 103a of the controller 103 is grounded, so that the relays RL20 and RL21 work and traveling contacts RL20-1 and RL21-1 shift from normal-closed contacts RL20-3 and RL21-3 to normal-opened contacts RL20-2 and RL21-2, respectively as shown in the figure with solid lines.
Whereby, an electric current flows from the power source 200 to the motors 101 through a terminal 103f of the controller 103, the normal-opened relay contact RL20-2, the traveling contact RL20-1 and a terminal 103d of the controller 103, and flows to the motor 102 from the power source 200 through the terminal 103f, the normal-opened relay contact RL21-2, the traveling contact RL21-1 and a terminal 103e of the controller 103, so that the motors 101 and 102 start their rotation.
When the respective wiper blades 52 and 53 depart from the stop positions D and D, the movable contacts 105a and 106a of the autostop switches 105 and 106 come in contact with the normal-opened fixed contacts 105c and 106c. Therefore, an electric current flows from the power source 200 to earth through the normal-opened fixed contact 105c of the autostop switch 105, the movable contact 105a, a terminal 103b of the controller 103, the diode D20, the capacitor C20, the terminal 103a of the controller 103 and the wiper switch 104, and through the normal-opened fixed contact 106c of the autostop switch 106, the movable contact 106a, a terminal 103c of the controller 103, the diode D21, the capacitor C21, the diode D23, the terminal 103a of the controller 103 and the wiper switch 104, thereby applying H-level potential to the base of the transistor Tr22 after charging the capacitors C20 and C21, so that the transistor Tr22 is turned on, and the transistors Tr20 and Tr21 are turned off. And the traveling contacts RL20-1 and RL21-1 of the relay RL20 and RL21 shift from the normal-opened contacts RL20-2 and RL21-2 to the normal-closed contact RL20-3 and RL21-3, respectively as shown in the figure with broken lines.
Accordingly, the wiper motors 101 and 102 continue to actuate the wiper blades 52 and 53 because an electric current flows from the power source 200 to the motors 101 and 102 through the normal-opened fixed contact 105c of the autostop switch 105, the movable contact 105a, the terminal 103b of the controller 103, the normal-closed contact RL20-3 of the relay RL20, the traveling contact RL20-1 and the terminal 103d of the controller 103, and through the normal-opened fixed contact 106c of the autostop switch 106, the movable contact 106a, the terminal 103c of the controller 103, the normal-closed contact RL21-3 of the relay RL21, the traveling contact RL21-1 and the terminal 103e of the controller 103.
When the respective wiper blade 52 and 53 arrive at the stop positions D and E after reciprocating on the respective window glasses 50 and 51, the movable contacts 105a and 106a of the autostop switch 105 and 106 shift to the normal-closed fixed contacts 105b and 106b, whereby the potential level at the terminals 103b and 103c of the controller 103 become low, but the transistor Tr22 is maintained in an ON-state since the H-level potential is applied to the base of the transistor Tr22 from the capacitors C20 and C21. Accordingly, the transistors Tr20 and Tr21 are kept in their OFF-states, the traveling contacts RL20-1 and RL21-1 of the relays RL20 and RL21 remain at the normal-closed relay contacts RL20-3 and RL21-3, thereby stopping the rotation of the motors 101 and 102.
The wiper motors 101 and 102 stop while the capacitors C20 and C21 are discharged, and the wiper blades 52 and 53 remain at their stop positions D and E, thereby setting intermittent time.
When the H-level potential ceases to be applied to the base of the transistor Tr22 after discharge of the capacitors C20 and C21, the transistor Tr22 is turned off and, the transistors Tr20 and Tr22 change to ON-states and excite relay coils of the relays RL20 and RL21, so that the traveling contacts RL20-1 and RL21-1 shift to the normal-opened relay contacts RL20-2 and RL21-2 as shown in figure with solid lines, and the wiper motor 101 and 102 start the rotation again.
In this time, for example, even if the wiper blade 52 arrives and stops at the stop position D, and the movable contact 105a of the autostop switch 105 disposed to the wiper motor 101 comes in contact with the normal-closed fixed contact 105b before the other wiper blade 53 arrives at the stop position E, the transistor Tr22 is maintained in the ON-state since the movable contact 106a of the autostop switch 106 disposed to the other wiper motor 102 is in contact with the normal-opened fixed contact 106c, the rotation of the wiper motor 102 continues until the wiper blade 53 arrives at the stop position E. In such a manner, the swinging motions of the wiper blade 52 and 53 are synchronized with each other.
In a case of changing the wiper switch 104 into a LOW position (low mode), the base of the transistor Tr22 is grounded and the transistors Tr20 and Tr21 are in the ON-state continually, and so the wiper motors 101 and 102 actuate the wiper blades 52 and 53 continuously regardless of the positions of the movable contacts 105a and 106a of the autostop switches 105 and 106 because the traveling contacts RL20-1 and RL21-1 are in contact with the normal-opened contacts RL20-2 and RL21-2 of the relays RL20 and RL21 as shown in the figure with solid lines at all times.
However, in the afore-mentioned conventional wiper apparatus 100 so structured as to stop the wiper motors 101 and 102 for an intermittent time depending on capacities of the capacitors C20 and C21 when the respective wiper blades 52 and 53 arrive at the stop positions D and E after reciprocating only one time on the window glasses 50 and 51, there is a problem in that raindrops and extraneous matters remain on the window glasses 50 and 51 and obstruct the view from the driver's seat pending the intermittent time of the wiper blades, thereby causing an obstruction to the driving of the motor vehicle in a case in which the intermittent mode of the wiper apparatus is selected in spite that the raindrops and the extraneous matters are attached on the window glasses 50 and 51 in large quantity.